Air conditioning method and apparatus



April 13, 1943.

J. E. WILSON 2,316,641

AIR CONDITIONING METHOD AND APPARATUS Filed Jan. 9, 1941 4 Sheets-Sheet 1 INVENTOR fines-,2. 14 1750. WW2: 41, 0%. 714mg.

' ATTORNEYS.

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April 13, 1943. J. E. WILSON AIR CONDITIONING METHOD AND APPARATUS Filed Jan. 9, 1941 WITH 777 MW con/n70;

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ATTORNEYS.

April 13,- 1943.

J. E. WILSON AIR CONDITIONING METHOD AND APPARATUS 4 Sheets- Sheet 4 Filed Jan. 9, 1941 ATTORNEY- Patented Apr. 13, 1943 James E. Wilson, Detroit, Mich, assignor to Chrysler Corporation, Detroit, Mich, a corporation of Delaware Application January 9, 1941, Serial No. 373,823

14 Claims. My present invention relates to air conditioning, in particular a means and method of eflecting an economy over present practices in the operation of air conditioning systems.

It is the principal object of the present invention to provide means whereby the amount of fresh air supplied to an enclosure in which people congregate in varying numbers is varied in proportion to the people load in the enclosure at any instant. Specifically, the invention comprises means for closing or opening to a greater or lesser extent a fresh air passage leading into the air conditioning system and supplying the enclosure with fresh air, such opening or closing varying in relation to the occupancy of the enclosure.

A further object of the present invention is to combine such fresh airvarying means with the variation of refrigerating effect achieved by a variable capacity compressor having means whereby the capacity of the compressor is varied in proportion to the total load on the air conditioning system. Specifically, the present invention comprises means whereby the means for causing variable capacity of the compressor of a compressor-condenser-expander system also effects variable capacity of the fresh air supply means.

It is an object of the present invention to achieve the foregoing objects with a minimum expenditure for equipment and installation so that the savings in operating expense may be almost entirely a true savings.

The objects and advantages of the present invention may be more clearly understood by reference to the accompanying drawings and the following specification wherein like numerals refer to like parts throughout. e

In the drawings, Fig. 1 is a schematic sectional view through a theater having the present invention applied thereto;

Fig. 2 is a sectional view taken through a compressor of variable capacity type as particularly disclosed in the patent to Neeson, No. 2,185,473, issued January 2', 1940, and having the apparatus of the present invention schematically associated therewith;

Fig. 3 is a'cha'rt showing the operating economy resulting from the useof the present invention,

and v Fig. 4 is an example of the present invention arranged to control a plurality of damper blades.

In Fig. 1 there is disclosed an enclosure,speciflcally a theater, having a space ill in which people congregate in varying numbers. -The space I! is served with conditioned air through ducts ii and i2 leading from a blower l3 having its inlet connected to an air conditioning expander casing l4. Air which is passed through the theater and warmed by the absorption of heat from the building and the occupants thereof returns to the expander casing i4 through a recirculating duct 15. Fresh air required by the occupants of the building is supplied through a fresh air inlet duct l6 joining the duct. ill at the inlet side of the casing l4.

The air passing into casing i4 is caused to 'traverse air cooling and dehumidifying means exemplified by expander coils 20 which are fed liquid refrigerant through the insulated pipe 2| leading from the condenser 22 of a condensing unit, comprising a motor: 23 and a variable capacity compressor 24, located in the basement or anteroom of 'the theater. The expanded refrigerant is returned to the compressor through the suction pipe 25 after achieving the work of cooling and dehumidifying the air passing through the coils 'or expanders 20. Suitable control means schematically indicated at 26 are provided to control the quantity of refrigerant supplied to the coils as is well understood in the arts of refrigeration and air conditioning. It is, of course, to be appreciatedthat any of numerous arrangements of theexpanders 20 in the casing M in conjunction with by-passes or other equipment may be utilized in the present. invention, such arrangements being well known throughout the air conditioning industry and any of which arrangements may be advantageously supple- I mented by my present invention.

1 have illustrated the invention as being used in conjunction with an automatically variable capacity compressor having unloader means to operating to load or to unload cylinders-oi the compressor automatically in responseto the total load on the expander means 20 as fully explained in the aforesaid patent. :Such loading and unloading in response to the total load on the expander means is a great economy in itself, but I have supplemented the-savings effected thereby by an additional savings eifected by the use of the present invention, as will presently appear.

In the Neeson compressor the gas compressed in the cylinders 4| passes into a discharge mam-- fold 4i and the discharge pipe 42 leading to the condenser 22 and liquid line H. The expanded refrigerant is returned to the compressor through suction pipe 25 and enters a suction manifold 43 having communication, such as through opening 44, with thespace '45 in which .bellows 48 of the unloader means is located. Oil for lubrication .of the compressor is placed under pressure by a pump 41 leading to oil supply passages as explained in the aforesaid patent. One of said passages leads to a master valve 66 which supplies oil to a plurality of tubes 6|, each leading to an individual cylinder unloading means including piston 52. As the total load on the expanders 20 varies, the pressure of the expanded refrigerant returning through pipe 26 into suction manifold 43 will tend to vary in direct proportion. Hence, the pressure in space 46 will vary as the load varies, and the bellows 46 will contract or expand as the load varies. This causes the application or discontinuance of oil pressure in a variable number of the tubes leading to the unloader pistons 52. As the oil pressure is applied against a piston 52, the piston will move toward the left from the position seen in Fig. 2 and will cause the cylinder associated therewith to commence operation, such action being the result of increased pressure in the suction manifold indicating that the total load on the ex- I panders is greater than the supply of refrigerant can accommodate. The increased supply occasioned by .the increased rate of compression causes the system to balance down to maintain the output of the air conditioning cabinet approximately at the desired value. load on the expanders drops off, the pressure in manifold 43 will be reduced so that bellows 46 will expand, and one or more of the tubes 5i will be disconnected from the source of oil pressure so that the pistons 52 associated therewith will move toward the right and cause the cylinders associated therewith to become ineffective. Thus, the variable capacity compressor effects an economy in operation since the horse power consumption of the motor 23 and the quantity of condensing water required vary directly as the load on the compressor 24 varies.

The foregoing explains the operation of the variable capacity compressor system in order that it may be seen that the present invention effects a further economy as follows: In an enclosure in-which the occupancy load varies from a peak to a negligible amount, it is, of course, necessary that fresh air be supplied at the peak occupancy period in a quantity sufficient to keep the air fresh and to avoid the accumulation of noxious gases and odors. Accordingly most installations make the fresh air inlet duct i6 of constant capacity designed to accommodate the peak load. I contemplate the use of a variable capacity fresh air inlet duct exemplified by the installation of dampers 60 in the duct, which dampers may be opened or closed to variabe extents in order to vary the capacity of the fresh air inlet duct. I control the opening and closing of the dampers 66 in response to the loading and unloading of the compressor since it is an obvious fact that the compressor will expand a practically constant part of its energy for maintaining the temperature of the conditioned air against the heat loss through the walls of the building. This building load is usually a constant load so that a constant number of cylinders will always be required to maintain the cooling eifect against the building load. It may vary, of course, as in a theater which has its greatest building load in the early evening and its lowest building load in the early morning, but during periods of occupancy it is safe to assume that the building load represents a fairly constant factor since the sun radiation is slowly absorbed and slowly dissipated. Therefore, any

If the total unloading of the cylinders after the compressor has been in operation a short while usually represents the falling of! of the occupancy load. I make use of this effect by associating with those pistons 62 which are affected by fluctuation of the total load on the compressor, means whereby the quantity of fresh air supplied to the system may be varied. Such means may take many forms, but I prefer the type schematically disclosed in Fig. 2 which comprises a flexible bellows or switch motor 6| connected to the pressure supply tube 6| or the space within which piston 62 operates. The bellows 6| operates a two-way switch lever 62 having contacts 63 thereon connected to battery or other source of power 64 through a wire 66. When the pressure is released from the unloading means associated with the individual bellows 6!, one of the com tacts 63 will engage a fixed contact 66 as shown in Fig. 2. This contact is connected through wire 61 to a contact 68 engageable by a contact 69 on a lever HI operated by a cam or circuit breaker ll. Lever III is connected by wire 12 to one of the windings (not shown) of a reversible motor 13 having its shaft directly connected to one of the dampers 60 and to the cam ll. The other end of the winding is connected by wire 14 to the opposite end of battery or the source of power. When oil pressure is supplied to the unloading means associated with the individual bellows 6|, the upper contact 63 will be disengaged from contact 66 and the lower contact 63 will engage a second fixed contact 16 connected by wire 16 to a fixed contact ll. Contact Ti is in position to be engaged by a contact 18 carried on a switch 1ever 13 operated by a second cam or circuit breaker l0 fixed to the shaft of motor 13. Lever 16 is connected by wire 6| to the reverse winding (not shown) of motor 13 and wire 14 leading back to the source of current.

The apparatus as shown in Fig. 2 is in position such that the oil pressure has been relieved and the cylinder 40 associated therewith is unloaded. When pressure is again supplied, indicating that a greater load is being placed on the expanders 20 by the return of more intensely heated air due to the effect of increased'occupancy, the lower contact 63 will be engaged with contact I6. Since lever 19 is on the high point .of cam 66, circuit will be made through the reverse winding of motor 13 and the damper 60 will open to admit a greater quantity of fresh air to the system. Cam II, which is out of phase with cam 60, proceeds to close contacts 66 and 69, and cam Ill proceeds to open contacts 11 and 18, resulting in the preparation of the otherwinding for subsequent action and the stopping' of motor 13 when damper 66 has reached a desired open position. When the pressure is relieved in the unloading mechanism for the lndividual cylinder, the upper contact 63 will engage contact 66 and, since contacts 63 and 66 are already engaged, the damper 60 will be moved back to its closed position and contacts 11 and 13 will be reengaged in preparation for another opening operation.

The foregoing is as simple and schematic as can be conceived. It is, of course, obvious that various forms of lever motors 6| actuated by pressure may be supplied and that various forms of circuit breakers or commutators may be fixed to the shaft of motor 13. Also, it is apparent that each of a plurality of dampers 60 may have a separate motor 13 and circuit associated therewith or that a more complicated control circuit or that the unlo'ader means may assume other forms.

For example, Fig. 4 shows a plurality of dampers 50, I60 and 260 arranged to control the air passing through the fresh air duct 5, the control apparatus and circuit for damper I60 being suitably designated by adding the prefix numeral I to each corresponding part of the control circuit for the damper 60, and the control circuit for the damper 260 being suitably designated by adding the prefix numeral 2 to each corresponding part. The-damper 260 is shown in open position due to the loading of the cylinder with which the switch operating bellows 28! is associated, the lever 262 having been moved to close the circuit including contacts 215, 211 and 218, and the motor having operated to open contacts 211 and 218 and to close contacts 268 and 269. The circuit is thus prepared for the unloading of the cylinder in which event'the circuit including contacts 266, 268 and 269 would be completed and the motor would .close the damper 260.

Fig. 3 discloses a chart setting forth the operating advantages achieved by the present inveni-ion. In this chart the required capacity in tons of refrigeration is shown on Scale A for a system which is assumed to require 75 tons at peak load. The time of operation is" shown on Scale B as that of a theatre which opens at 7 p. m. and closes 'at 11 p. m. The occupancy, as represented by number of people, is shown on Scale C, in the present example the theater being assumed to have a peak occupancy load of fifteen hundred people. The building load is assumed as being a straight heat loss throughout the period from 7 p. m. to 11 p. m. of approximately 10.8 tons as represented by curve E. The fresh air load, based on peak occupancy at 9 p. m., is shown for a standard constant fresh air load system as approximately 14.4 tons from 7 p. m. to 11 p. m. on curve F. The required fresh air load based on instantaneous occupancy from '7 p. m. to 11 p. m. is represented on curve G as being negligible at '7 p, m., reaching a peak of 14.4 tons at 9 p. m., and falling off to zero at 11 p. m. This required fresh air load is based upon 5 C. F. M. fresh air per occupant as represented by the occupancy curve D which is zero at 7 p. m.,,reaches a peak of fifteen hundred people at 9 p. m., and falls off to zero at 11 p. m. The people oad occasioned by the occupancy is represented y curve H as extending from zero at 7 p. m. tp 50 tons at 9 p. m. and falling off to zero at 11 p. m. The total required capacity with standard constant fresh air control using a variable capacity compressor is shown on curve I, this curve being the summation of curve E representing the building load, curve F representing a constant peak 00- cupancy fresh air load, and curve H representing the people load. This curve, of course, extends from a total of 25.2 tons at 7 p. m., reaches a peak of 75 tons at 9 p. m., and falls off to 25.2 tons at 11 p. m. The total required capacity with the present invention is represented by curve J, this curve being the summation of the required occupancy fresh air load curve G, the building load curve E, and the people load curve H. This curve begins at 10.8 tons at 7 p. m., reaches a peak of 75 tons at 9 p. m., and falls off to 10.8 tons at 11 p, m. The space or area between curves I and J represents the saving in tonhours of refrigeration made by use of the present invention.

In the above example it may be demonstrated that the saving is approximately ton-hours of refrigeration. It is practically axiomatic that one kilowatt-hour input is required per ton-hour of refrigeration. Hence, the savings in an even ing's operation is approximately 25 kilowatthours. Assuming an average power rate of 2 cents per kilowatt-hour, there is effected a saving of approximately 62 /2 cents per night on power consumption. Assuming an average consumption of 3 gallons per minute per ton of refrigeration, the water saving is approximately 600 cu. ft. per night of operation. At 40 cents per 1,000 cu. ft. this amounts to 24 cents per night saved on water. In a season consisting of one hundred nights, this combined power and water saving amounts to $86.50; and in a normal life expectancy of fifteen years, this amounts to $1,297.50, which is a large part of the original cost of the average 75-ton condensing unit. The

above figures are based on countrywide averages of power cost, condenser cooling water temperatures, and water costs. In some localities the above figures may be lower and in some they maybe far higher. In any event, it is readily apparent that the present invention achieves an operatingeconomy of considerable magnitude.

Having explained the operation and advantages of a simple form of the present invention, it should be apparent to those skilled in the art that the invention may assume numerous modifications in detail and arrangement, particularly as hereinbefore pointed out. All such modifications as come within the scope of the following claims are considered to be a part of my invention.

I claim:

1. An air conditioning system comprising a compressor-condenser-expander system of refrigeration, said compressor comprising means to vary the rate of compression of refrigerant in response to the total load on said expander, air circulating means for passing a stream of air in heat transferring relation with said expander and into the enclosure being conditioned, means to supply recirculated air from said enclosure to form a variable part of said stream, means to supply fresh air from outside of said enclosure to form the variable remainder of said stream, and means to vary the proportion of fresh to recirculated air in response to changes in the rate of compression of said refrigerant by said compressor.

2. An air conditioning system comprising a compressor-condenser-expander system of refrigeration, said compessor comprising means to vary the rate of compression of refrigerant in response to the total load on said expander, air circulating means for passing a stream of air in heat transferring relation with said expander and into the enclosure being conditioned, means to supply recirculated air from said enclosure to form a variable part of said stream. means to supply fresh air from outside of said enclosure to form the variable remainder of said stream, and means to control the ratio of fresh to recirculated air in response to changes in the back pressure of said compressor-condenser-expander system.

3. An air conditioning system comprising a compressor-condenser-expander system of refrigeration, said compressor comprising means to vary the rate of compression of refrigerant in response to the total load on said expander, air,

circulating means for passing a stream of air in heat transferring relation with said expander and into the enclosure being conditioned, means to supply recirculated air from said enclosure to form a variable part of said stream, means to supply fresh air from outside of said enclosure to form the variable remainder of said stream, damper means in said fresh air supply means, means responsive to the back pressure of said system to increase or decrease the rate of compression by said compressor as the back pressure rises or falls, respectively, and means simultaneously effective to open or close said damper means as the back pressure rises or falls, respectively.

4. An air conditioning system comprising a compressor-condenser-expander system of refrigeration, said compressor comprising a plurality of cylinders and means automatically to vary the number of cylinders in operation in response to variations in the load on said expander, air circulating means comprising means to pass a variable mixture of fresh and recirculated air in heat transferring relation with said expander, damper means to vary the quantity of fresh air supplied to said air circulating means, and means to move said damper means from one position to a position admitting a greater quantity of fresh air in response to the placing in operation of a cylinder of said compressor.

5. An air conditioning system comprising a compressor-condenser-expander system of refrigeration, said compressor comprising a plurality of cylinders and means automatically to vary the number of cylinders in operation in response to variations in the load on said expander, air circulating means comprising means to pass a variable mixture of fresh and recirculated air in heat transferring relation with said expander, damper means to vary the quantity of fresh air supplied to said air circulating means, means to move said damper means from oneposition to a position admitting a greater quantity of fresh air in response to the placing in operation of a cylinder of said compressor, and means whereby said damper opening means and the damper means controlled thereby are returned to their initial positions in response to taking said cylinder out of operation. v

6. An air conditioning system comprising a compressor-condenser-expander system of refrigeration, said compressor comprising a plurality of cylinders each having a fluid pressure operated unloader mechanism associated therewith, means for creating fluid pressure when said compressor is in operation, a master valve for connecting or disconnecting fluid under pressure supplied by said pressure creating means to or from individual cylinder unloading means, means responsive to the back pressure of the system to operate said master valve variably in proportion to the back pressure of the system in order to vary the number of cylinders in operation in proportionto the load on the expander, fluid pressure operated switch operating means associated with one of saidfluid pressure operated unloader mechanisms and arranged for movement from one position to another when the cylinder associated therewith is loaded or unloaded, an air supply duct leadingto said expander, damper means in said air supply duct, a damper motor arranged to move said damper means to admit a greater or lesser quantity of air to said air supply duct, and a control circuit for said motor including switching means controlled by said switch operating means to cause said motor to move said damper means toward open or closed position in unison with the loading or unloading of said cylinder.

7. An air conditioning system comprising a compressor-condenser-expander system of refrigeration, said compressor comprising a plurality of cylinders each having a fluid pressure operated unloader mechanism associated therewith, means for creating fluid pressure when said compressor is in operation, a master valve for connecting or disconnecting fluid under pressure supplied by said pressure creating means to or from individual cylinder unloading means, means responsive to the back pressure of the system to operate said master valve variably in proportion to the back pressure of the system in order to vary the number of cylinders in operation in proportion to the load on the expander, a plurality of fluid pressure operated switch operating means each associated with one of said fluid pressure operated unloader mechanisms and arranged for movement from one position to another when the cylinder associated therewith is loaded or unloaded, an air supply duct leading to said expander, damper means in said air supply duct, damper operating means arranged to move said damper means to admit a greater or lesser quantity of air to said air supply duct, and a control circuit for said damper operating means including switching means controlled by said switch operating means to cause said damper operating means to move said damper means toward open or closed position in accordance with the loading or unloading of the cylinders having such switch operating means associated therewith.

8. An air conditioning system comprising a compressor-condenser-expander system of refrigeration, said compressor comprising a plurality of cylinders each having a fluid pressure operated unloader mechanism associated therewith, means for creating fluid pressure when said compressor is in operation, a master valve for connecting or disconnecting fluid under pressure supplied by said pressure creating means to or from individual cylinder unloading means, means responsive to the back pressure of the system to operate said master valve variably in proportion to the back pressure of the systemin order to vary the number'of cylinders in operation in proportion to the load on the expander, fluid pressure operated switch operating means associated with one of said fluid pressure operated unloade mechanisms and arranged for movement from one position to another when the cylinder associated therewith is loaded or unloaded, a recirculated air duct and a fresh air supply duct leading to said expander, damper means in said air supply ducts, a damper motor arranged to move said damper means to vary the proportion of fresh to recirculated air admitted to the expander through said ducts, and a control circuit for said motor including switching means controlled by said switch operating means to cause said motor to move said damper means to admit more or less fresh air in unison with the loading or unloading of said cylinder.

9. An air conditioning system comprising a compressor-condenser-expander system of refrigeration, said compressor comprising a pinrality of cylinders each having a fluid pressure operated unloader mechanism associated therewith, means for creating fluid pressure when said compressor is in operation, a master valve or from individual cylinder unloading means, means responsive to the back pressure of the system to operate said master valve variably in proportion to the back pressure of the system in order to vary the number of cylinders in operation in proportion to the load on the expander, a plurality of fluid pressure operated switch operating means each associated with one of said fluid pressure operated unloader mechanisms and arranged for movement from one position to sponse to the pressure of the refrigerant returned to the compressor from the expander of the system.

another when the cylinder associated therewith is loaded or unloaded, a recirculated air supply duct and a fresh air supply duct leading to said expander, damper means in said air supply ducts, damper operating means arranged to move said damper means to vary the proportion of fresh to recirculated air admitted to the expander through said ducts, and a control circuit for said damper operating means including switching means controlled by said switch operating means to cause said damper operating means to move said damper means to admit more or less fresh air in accordance with the loading or unloading of the cylinders having such switch operating means associated therewith.

10. The method of air conditioning an enclosure comprising circulating a constant quantity of air consisting of variable amounts of air from the enclosure and fresh air from outside the enclosure over cooling and dehumidifying means and into the enclosure, circulating a volatile refrigerant through a compressor-condenser-expander system of refrigeration of which the expander comprises said air cooling and dehumidifying means, varying the rate of circulation of refrigerant in proportion to the pressure of the refrigerant leaving the expander, and varying the proportion of fresh air circulated in proportion to the rate of circulation of the refrigerant.

11. The method of air conditioning an enclosure comprising circulating a constant quantity of air consisting of variable amounts of air from the enclosure and fresh air from outside the enclosure over cooling and dehumidifying means and into the enclosure, circulatinga'volatile refrigerant through a compressor-condenser-expander system of refrigeration of which the expander comprises said air cooling and dehumidifying means, and varying the rate of circulation of re- '12. The method of air conditioning comprising circulating a constant quantity of air consisting of variable amounts of air from the enclosure being served and fresh air from outside of the enclosure in heat transferring relation with the refrigerant expander of a compressor-condenserexpander system of refrigeration, varying the rate of compression of the refrigerant used in said system in accordance with variations in the back pressure of said system, and varying the proportion of fresh air to the recirculated air in said constant quantity of circulating air in accordance with variations in the back pressure of said system.

13. The method of air conditioning comprising circulating a constant quantity of air consisting of variable amounts of air from the enclosure being served and fresh air from outside of the I enclosure in heat transferring relation with the refrigerant expander of a compressor-condenserexpander system of refrigeration, varying the rate of compression of the refrigerant used in said system in accordance with variations in heat load on said expander, and varying the proportion of fresh air to the recirculated air in said constant quantity of circulating air in proportion to the changes in the rate of compression of the refrigerant.

14. The method of air conditioning comprising circulating a constant quantity of air consisting of variable amounts of air from the enclosure beingserved and fresh air from outside of the enclosure in heat transferring relation with the refrigerant expander of a compressor-condenserexpander system of refrigeration, varying the rate of compression of the refrigerant used in said system from a minimum calculated to take care of the load on said expander when the enclosure is empty of people to a maximum'calculated to take care of the load on said expander when the enclosure is empty of' people plus the load imposed on the expander by filling the enclosure with people automatically in response to changes in the total load on the expander, and varying the proportion of fresh air to the recirculated air in said constant quantity of circulating air in response to changes in the rate of compression of the refrigerant.

JAMES E. WILSON. 

